Positive and perky Amazing Race hopefuls Emily and Jono Trenberth may seem like sweeties at first but underneath lies a fierce competitive streak which they hoped to use to their advantage.

This year's Amazing Race pits New Zealand against Australia in a trans-Tasman showdown.

The teams are out to win but this time they also carry their nation's pride on their shoulders.

Teams follow clues in a race around the world, crossing ten countries. The winner of the series is the first team to finish the final leg and collect the grand prize of $250,000.

The Christchurch duo were nicknamed the 'Von Trapps' during filming because of a habit of breaking out into song and dance at odd times. But older brother Jono, 26, said their serious side was hard at work too.

''We've been through so much together as a family that no matter what happened our relationship was always going to be solid. Where other teams would sort of fall apart and fight and bicker, we always knew at the end of the day we would stay strong.''

Emily works as a model and dancer when she isn't studying radiography. She still lives in Christchurch while Jono has made the move to Wellington where he works in advertising.

The pair always had a pact that they would travel the world together, Emily, 24, said.

"It is the most best reality TV show you could possibly be on... Dad always said if you're ever going to travel the world, go with someone who will share it with you for a life time.''

Apart from a bit of 'mumming' of her brother and the odd argument, the Trenberths say they came out of the experience incredibly proud of each other.

''Emily made me really proud. Every moment that Emily was doing some sort of challenge I was completely beside myself with pride...she killed everything that she did,'' Jono said.

He said it would be interesting to see how they were portrayed after being nicknamed the 'hot siblings' and the 'Von Trapps'.

The theme this year is a race within a race and the pair said this made the competition less about themselves and more about going the distance for New Zealand.

Starting off the season in Christchurch meant the team could work their home-town advantage and they said the overwhelming feedback from the other contestants was that Canterbury was the most beautiful place they visited throughout the show's filming.